Prostaglandin synthesis by, and the effects of prostaglandins and prostaglandin analogues on, the vas deferens of the rabbit and rat in vitro.

Abstract

Summary. The endogenous concentrations of three PGs in the vas deferens of rabbits and rats were low (5–50 ng/100 mg tissue), although PGE-2 and PGF-2α were present in greater quantities than 6-keto-PGF-1α. Homogenates of rat and rabbit vas deferens synthesized these three PGs in large quantities during a 90 min incubation period. PGE-2 was the major PG synthesized by the rat vas deferens, followed by PGF-2α and 6-keto-PGF-1α. PG production by the rabbit vas deferens was lower than in the rat and PGF-2α was the major PG formed. None of the prostanoids tested (PGE-1, PGE-2, PGD-2, ICI 79939, ICI 81008 (fluoprostenol), 9,11-epoxymethano PGH-2, and 11,9-epoxymethano PGH-2) in concentrations up to 1–20 μg/ml altered the tone of the rabbit or rat vas deferens. PGI-2 was more potent than PGE-2 or PGF-2α in potentiating responses of the rabbit vas deferens to noradrenaline but was less potent than PGF-2 or PGE-1 in inhibiting responses to field stimulation. No consistent effects of these three PGs on responses of the rat vas deferens to noradrenaline administration were observed. PGE-2 and PGE-1, but not PGI-2, had only a small inhibitory effect on the responses of the rat vas deferens to field stimulation. None of the other prostanoids tested affected the responses of the vas deferens to noradrenaline or to field stimulation in either species. It is concluded that, while PGs may not directly affect the tone of the vas deferens, they may affect the contractility of the vas deferens by pre-junctional actions in the rabbit and rat, and by post-junctional actions in the rabbit. These actions of PGs (confined to PGE-2, PGF-2α and PGI-2) may influence sperm transport along the vas deferens.